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Displaying 2026 - 2050 of 2503

Sensitivity Comparison of Mx and Frequency Modulated Bell-Bloom Cs Magnetometers in a Micro-Fabricated Cell

February 1, 2010
Author(s)
Ricardo Jimenez Martinez, William C. Griffith, Ying-ju Wang, Svenja A. Knappe, John E. Kitching, Ken Smith, Mark Prouty
We compare the sensitivity performance of two optically pumped atomic magnetometers based on the Mx and frequency-modulated Bell-Bloom configurations. The Cs magnetometers are implemented using a millimeter-scale microfabricated vapor cell in a

Spin-transfer dynamics in spin valves with out-of-plane magnetized CoNi free layers

January 29, 2010
Author(s)
William H. Rippard, Alina M. Deac, Matthew R. Pufall, Justin M. Shaw, Mark W. Keller, Stephen E. Russek, Gerrit E. Bauer, Claudio Serpico
We have measured spin-transfer-induced dynamics in magnetic nanocontact devices having a perpendicularly magnetized Co/Ni free layer and an in-plane magnetized CoFe fixed layer. The frequencies and powers of the excitations agree well with the predictions

Symmetry and Fourier analysis of the ab-initio-determined torsional variation of structural and Hessian-related quantities for application to vibration-torsion-rotation interactions in CH3OH

January 11, 2010
Author(s)
Li-Hong Xu, Jon T. Hougen, Jonathan M. Fisher, Ronald M. Lees
The aim of the present paper is to investigate the use of quantum chemistry calculations to obtain the torsional dependence of various structural and vibrational-force-field-related quantities that could help in estimating the vibration-torsion-rotation

NIST Time and Frequency Bulletin

January 5, 2010
Author(s)
Eyvon Petty
The Time and Frequency Bulletin provides information on performance of time scales and a variety of broadcasts (and related information) to users of the NIST services)

Comparison of the NIST and PTB Standards for Air Kerma and Low-Energy X-rays

December 31, 2009
Author(s)
C M. O'Brien, L. Buermann
A comparison has been made of the air-kerma standards for low-energy x-rays at the National Institute of Standards and Technology (NIST) and the Physikalisch-Technische Bundesanstalt (PTB). The comparison involved a series of measurements at the PTB and

Radiochromic Film

December 31, 2009
Author(s)
Christopher G. Soares, Sameul Trichter, Slobodan Devic
Media that turns color upon being irradiated (coloration detectors) were some of the earliest available detectors for ionizing radiation. Besides conventional silver halide photographic media, which aided in the discovery of x-rays by Rontgen, barium

Progress Toward Corrugated Feed Horn Arrays in Silicon

December 16, 2009
Author(s)
Joseph W. Britton, Ki W. Yoon, James A. Beall, Daniel T. Becker, Hsiao-Mei Cho, Gene C. Hilton, Michael D. Niemack, Kent D. Irwin
We are developing monolithic arrays of corrugated feed horns fabricated in silicon for dual-polarization single mode operation at 90, 145 and 220 GHz. The arrays consist of hundreds of platelet feed horns assembled from gold coated stacks of micromachined

Compensation of Field-Induced Frequency Shifts in Ramsey Spectroscopy of Optical Clock Transitions

December 10, 2009
Author(s)
A. V. Taichenachev, V. I. Yudin, Christopher W. Oates, Barber W. Zeb, Nathan D. Lemke, Andrew Ludlow, U Sterr, Ch. Lisdat, F Reihle
We develop a modified version of Ramsey spectroscopy that uses an additional frequency shift to compensate frequency shifts induced by the excitation itself. In its simplest realization, this method uses a small step of the probe frequency during the two

Long-term comparison of caesium fountain primary frequency standards

December 7, 2009
Author(s)
Thomas E. Parker
There are currently nine caesium fountain primary frequency standards regularly reporting calibrations of International Atomic Time to the Bureau International des Poids et Measures (BIPM). An investigation has been carried out using data from the BIPM

Extension of the resonance line series of Mg III

December 1, 2009
Author(s)
C M. Brown, Alexander Kramida, Uri Feldman, Joseph Reader
Spectra of Mg emitted by a Penning discharge were recorded in the extreme ultraviolet (EUV) on a 10.7-m grazing-incidence spectrograph with phosphor image plates. The spectra provided nine new lines of Mg III between 156 and 166 Å and allowed us to improve

Ultra-Sensitive Optical Measurements of High-J Transitions in the O2 A-band

November 24, 2009
Author(s)
Daniel K. Havey, Joseph T. Hodges, David A. Long, Mitchio Okumura, Charles E. Miller
We report frequency-stabilized cavity ring-down spectroscopy measurements of high-J O2 A-band magnetic dipole line parameters. Our goals were to measure intensities and line shape parameters for the primary isotopologue of O2 in the A-band region and to

Limits on GPS Carrier Phase Time Transfer

November 16, 2009
Author(s)
Marc A. Weiss
The stability of differential delays between Global Navigation Satellite receivers is critical for time and frequency transfer. We study the limit of this transfer between two specific receivers from the study of data taken from these receivers while they

Novel, All-Digital Phase Measurement System for Time Scales

November 16, 2009
Author(s)
Stefania Romisch, Thomas E. Parker, Steven R. Jefferts
A novel, all-digital phase measurement system, to be utilized as part of the NIST Time Scale at NIST in Boulder, CO is presented. The system is used to compare output signals from several commercial atomic frequency standards: the phase differences between

Phase-lock Loops in Vibration Environments

November 16, 2009
Author(s)
Archita Hati, Craig W. Nelson, David A. Howe
A popular scheme for achieving low phase noise across a large range of offset frequencies is to employ an oscillator at an output frequency with low far-from-carrier noise that is phase-locked to a reference that has low close-to-carrier noise. We

Progress on a Portable Rubidium Fountain Frequency Standard

November 16, 2009
Author(s)
Paul D. Kunz, Thomas P. Heavner, Steven R. Jefferts
We are developing a transportable laser-cooled rubidium (Rb) atomic fountain frequency standard. We have a complete optical package, and have recently shown cooled, launched, and detected atoms. Additionally, a new physics package has been designed and is

Two-Way Satellite Time and Frequency Transfer Using 1 MChip/S codes

November 16, 2009
Author(s)
Victor S. Zhang, Thomas E. Parker, Demetrios Matsakis, Joseph Achkar, Daniele Rovera, Dirk Piester, Andreas Bauch, Luca Lorini
The Ku-band transatlantic and Europe to Europe two-way satellite time and frequency transfer (TWSTFT) operations used the 2.5 MChip/s pseudo-random codes with 3.5 MHz bandwidth until the end of July, 2009. The cost of TWSTFT operation is associated with

Realization of a programmable two-qubit quantum processor

November 15, 2009
Author(s)
David Hanneke, Jonathan Home, John D. Jost, Jason Amini, Dietrich G. Leibfried, David J. Wineland
The universal quantum computer is a device that could simulate any physical system and represents a major goal for the field of quantum information science. Algorithms performed on such a device are predicted to offer significant gains for some important

Optical frequency stabilization of a 10 GHz Ti:sapphire frequency comb by saturated absorption spectroscopy in 87Rubidium

November 4, 2009
Author(s)
Dirk Heinecke, Albrecht Bartels, Tara M. Fortier, Danielle Braje, Leo Hollberg, Scott A. Diddams
The high power per mode of a recently-developed 10 GHz femtosecond Ti:sapphire frequency comb permits nonlinear Doppler-free saturation spectroscopy in 87Rubidium with a single mode of the comb. We use this access to the natural linewidth of the Rubidium

Preparation of Dicke States in an Ion Chain

November 2, 2009
Author(s)
David Hume, Chin-Wen Chou, Till P. Rosenband, David J. Wineland
We have investigated theoretically and experimentally a method for preparing Dicke states in trapped atomic ions. We consider a linear chain of N ion qubits that is prepared in a particular Fock state of motion, jmi. The m phonons are removed by applying a
Displaying 2026 - 2050 of 2503
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